New Genetic Clues to Cause of Parkinson's

June 24, 2011 -- Researchers have identified two new genetic variants linked to Parkinson's disease and say they now know how big a role heredity plays in the neurodegenerative disorder.

About a dozen genetic associations with Parkinson's have been confirmed, and many more remain to be discovered, says researcher Nicholas Eriksson, PhD, of the California-based direct-to-consumer gene testing company 23andMe.

In their new study, published this week in the journal PLoS Genetics, Eriksson and colleagues estimated that about a quarter of the variation in susceptibility to the disease is due to genetic factors.

"Each new genetic variant we find gets us a little bit closer to being able to see the full picture of how genes impact this disease," Eriksson tells WebMD. "Roughly 10 genetic variants that contribute to Parkinson's had been found and we added another two to the list."

Role of Genes in Parkinson's

The exact causes of Parkinson's disease are not known, but researchers now believe that both environmental triggers and genetic influences play a role.

Genetic variants have been implicated in the small percentage of cases that occur in people under the age of 50, known as early-onset Parkinson's. But much less is known about the role of genes in late-onset disease.

In an effort to better understand genetic influences in both early- and late-onset Parkinson's, Eriksson, study researcher Chuong B. Do, PhD, and colleagues conducted a novel genome-wide study involving around 3,400 Parkinson's patients and close to 30,000 people without the disease who were 23and Me clients.

The Parkinson's patients were recruited with the help of the Michael J. Fox Foundation, the Parkinson's Institute, and the National Parkinson's Foundation. The study was funded solely by the genetic testing company, however.

Genome-wide association studies became possible following the completion of the Human Genome Project and other landmark projects around the middle of the decade, which provided tools that allow researchers to look for genetic contributions to common diseases.